Bansode N.V.,Mahindra Two Wheelers Ltd |
Ganguly A.,Mahindra Two Wheelers Ltd |
Agarwal V.K.,Mahindra Two Wheelers Ltd
SAE International Journal of Engines | Year: 2016
A single cylinder gasoline engine of a sports bike generates sufficient hot gases to pose great challenge to the designers of exhaust system. The high temperature exhaust gases in muffler creates thermal elongation on the solid parts of exhaust system, which is mounted on the chassis. This arrangement induces thermal stress in exhaust assembly. It is necessary to analyze this thermal stress to ensure the durability of muffler components. The exhaust design has a diversion at the header pipe to distribute the flow in two branches. This junction and the branches heated up excessively and showed repeated failure. To analyze the thermal stress, the temperature distribution in the muffler components is obtained from Computational Fluid Dynamics (CFD) analysis. The complete motorcycle with detailed exhaust system is modelled in the standard wind tunnel using a commercial CFD software. Conjugate heat transfer (CHT) study is done for normal and adverse operating conditions considering transfer of heat between hot exhaust gases passing through muffler assembly, muffler solid components and external air flowing over motorcycle. The heat generation in the catalytic convertor and the radiation between muffler components are also considered. Parallelly, complete muffler assembly is modelled in a commercially available FEA code. All the muffler mountings are considered including the bushings and bolted connections. Material properties are defined for each of the muffler components. The temperature distribution obtained from CFD analysis is applied to simulate for thermal expansion, stress and deformation in the exhaust system. Results showed excessive stress on a certain component of the muffler. Design modification is implemented and is validated following similar analysis work flow. Thermal stress is found to have reduced considerably in the modified design as compared to the base design. Copyright © 2016 SAE International.
Ganesan A.,Mahindra Two Wheelers Ltd. |
Sundaram S.,Mahindra Two Wheelers Ltd.
SAE Technical Papers | Year: 2012
State of Charge (SOC) of a storage battery gives the capacity remaining in the battery to meet the load demands. SOC of a Lead Acid battery is predicted based on the temperature compensated value of electrolytes' specific gravity (Sp. gr.). Since measuring specific gravity is not possible in an automobile under dynamic conditions, Open Circuit Voltage (OCV) is used as the parameter to predict the SOC. But OCV can indicate SOC accurately only after a sufficient period of rest of a battery in any condition. Also it varies between batteries due to several factors like temperature, ageing, electrolyte volume, internal construction, etc. Predicting the SOC of battery theoretically depends on number of equations developed to accommodate these variables. Hence for a real time estimation of SOC of battery, a Heuristic algorithm is suggested. The initial State of Battery is estimated by temperature compensated OCV Vs SOC characteristics and followed by dynamic prediction of SOC using Coulomb or Energy Measurement. The drawback of cumulative error in energy measurement is also overcome in this algorithm. For improving the accuracy of dynamic prediction, the heuristic algorithm also talks about compensating the predicted SOC value with respect to factors such as rate of discharge, rate of charge, self discharge and temperature. Finally, the algorithm also talks about "A Self learning feature", to predict OCV based the initial SOC of Lead Acid battery more accurately irrespective of the vehicle quiescent current differences. Copyright © 2012 SAE International.
Menon M.,Mahindra Two Wheelers Ltd |
Kakaye S.,Mahindra Two Wheelers Ltd |
Sundaram S.,Mahindra Two Wheelers Ltd
SAE Technical Papers | Year: 2016
The world today is moving more towards convenience and luxury. Auto manufacturers are being constantly challenged to provide innovative additions to conventional vehicles in terms of attractive features. This paper describes one such invention proposed to add convenience and novelty to the use of two wheelers. The proposed system is called a "Keyless Scooter". Derived from the idea of keyless entry in four wheelers, the system aims at extending this luxury to a larger band of population in India, i.e. users of two wheeled vehicles. The system eliminates use of a mechanical lock and key arrangement. All functions carried out by the mechanical arrangement of lock and key are replaced with an equivalent electronic system. A "Keyless Scooter" is one in which a user can just approach it with a key fob on himself/herself and start the vehicle, open the luggage box, etc. without having to insert a key physically into the lock body. The vehicle is designed to communicate with the key fob wirelessly thus retaining the core requirement of a lock and key arrangement-Exclusivity. This paper describes the "Keyless Scooter" in detail, covering design considerations, vehicle interfacing and choice and arrangement of electromechanical sub-systems. Further, it goes on to explain the algorithm employed to intelligently maintain convenience without compromising on safety and security. To conclude, this document describes the prototype built on a scooter platform and also describes the failure modes associated with this design, corresponding counteractions taken for the same and future scope. © Copyright 2016 SAE International.
Santra T.S.,Mahindra Two Wheelers Ltd. |
Agarwal V.K.,Mahindra Two Wheelers Ltd. |
Bhambri M.,Automotive CAE
SAE Technical Papers | Year: 2016
This paper depict the difference in the endurance factor of safety with usage of static and quasi static FE analysis and corrective measures take to solve the problem. The importance of the dynamic loading and subsequent effect of it on the multi axial fatigue analysis. Considering the modern trend prevailing among the vehicle manufacturers and specifically talking about two wheeler industry, it is clear that while the engine remains the same but the frame is changed to cater the market with new models to cut down on the development time. Initially the crankcase was designed for a double cradle frame where the crankcase was mounted on the frame. Later, the frame design was changed to single cradle where engine acts as a stress member link. This kind of arrangement makes the crankcase mountings participate in the chassis loads. Therefore, the crankcase mounting experiences road loads when the vehicle encounter the road irregularities. Earlier the design was verified by static simulation, where the maximum force and the moment were applied for FEA analysis, the results of which couldn't capture the fluctuation in the load and resulting in greater FOS. The quasi static analysis generated cyclic stress files which was used to determine the endurance factor of safety. The results showed very low factor of safety and thus, the existing crankcase mounting could not be used for the stress member proposal. The mounting were required to be modified to increase the endurance factor of safety. The mounting were brought closer to the crankcase and were reinforced with ribs. This helped us to use same crankcase for different type of frames. © 2016 SAE International.
Pradeepak R.,Automotive CAE |
Kumbhar S.,Mahindra Two Wheelers Ltd.
SAE Technical Papers | Year: 2016
At present, vehicle testing in laboratory is one of the important phase to quicken the product validation process. In the early phase of laboratory testing it is required to evaluate the strength of the vehicle structure through physical rig setup which represents the consumer's usage. Two and Multiple poster input excitation are among the laboratory rig testing to represent the actual road are used to predict the durability of vehicle components. The road inputs through the poster are known as drive files, a feedback controlled system which reproduces the track or real road recorded specimen's accelerations, displacements and strains in laboratory. Derivation of drive files in poster testing requires iteration of physical specimen to exactly replicate the actual road. This paper discusses about generation of drive files as inputs for poster actuation with virtual model(as a substitute for actual model)which is applicable in areas of vehicle durability and ride comfort studies. For the reason to minimize the time,cost,man-machine hours and energy, an automation is developed to simulate the validated virtual model with iterations process to generate the road files for further use in physical and virtual test.The paper details on the procedure followed traditionally and what changes have been made in the current process to generate road drive input files. © Copyright 2016 SAE International.
Khan S.A.,Mahindra Two Wheelers Ltd |
Dhongde S.,Mahindra Two Wheelers Ltd
SAE Technical Papers | Year: 2014
A small single cylinder 4 stroke gasoline engine varying capacity from 100cc to 500cc generally used for two wheelers has a wide range of load conditions. Such variation in load on engine demands variation in Transmission ratio at different vehicle speeds for optimum performance, drivability and Economy. A scooter has continuously variable transmission called as CVT which is generally centrifugally controlled with respect to engine speed as against that of series of manual gears used in motor cycle. The work aims at creating a mathematical model for controlling variation in transmission ratio of CVT by converting the generally centrifugally controlled CVT by electronic control. The objective is to implement the mathematical model with a novel electronic controlled CVT in a two wheeler engine for the improvement in performance. The mathematical model done through geometric calculations and modeling is discussed in details. The mathematical model is compared with the actual testing data to validate the calculations and results. Thus with this mathematical model and mechanism we can achieve a variation in engine transmission ratio as per load demand. The work explains the impact of mathematical model for controlling CVT ratio installed on the two wheeler engine and hence will resultant improvement in performance in terms of drivability and economy of a vehicle. On the whole it concludes that this mathematical model can be implemented on small engines for better performance. Copyright © 2014 SAE International.
Khan S.A.,Mahindra Two Wheelers Ltd. |
Ayyappath P.,Mahindra Two Wheelers Ltd.
SAE Technical Papers | Year: 2014
A small single cylinder 4 stroke gasoline engine varying capacity from 100cc to 1000cc generally used for two wheelers has a wide range of engine speeds during operation and may vary from 1000 RPM to 10000 RPM. Such variation in speed of engine demands variation in the valve timing and lift of engine at different speeds for optimum performance. The work aims at improving the performance of single cylinder two wheeler gasoline engine. The objective is to implement the novel variable valve timing and lift mechanism in the two wheeler single cylinder 4 stroke gasoline engine for the improvement in performance. The system design through kinematic calculations and 3D modeling, the prototyping with assembly, the functioning of system and its effect on the performance of engine are discussed in details. Valve timing and lift optimization was done using 1D simulation for performance prediction. The system includes a spring operated switching mechanism by which we achieve variation in valve timing and lift of intake valve at different speed range. The system is made compact to accommodate in the extremely small space of a single cylinder 110cc 4 stroke SOHC engine generally used in scooters and motorcycles. An electronic control circuit and DC motor is used to sense speed and actuate the mechanism respectively. Thus with this mechanism we achieve a variation in engine valve timing and lift at different speed range of the engine in stages. The mechanism was assembled and tested on engine dynamometer for studying operation of the mechanism on the engine at various speeds. The work explains the impact of system prototype when installed on the two wheeler engine and resulting improvement in Volumetric Efficiency and Torque of Engine, hence a reduction in fuel consumption. On the whole it concludes that this system can be implemented on small engines for better performance. Copyright © 2014 SAE International.
J A.P.,Mahindra Two Wheelers Ltd. |
Agarwal V.K.,Mahindra Two Wheelers Ltd.
SAE Technical Papers | Year: 2014
Piston is a very important part of the engine as the contribution to its efficiency and performance is huge. This study is to understand in detail, the effect of piston skirt design on the functioning of an engine. A small gasoline engine was taken up for study. A commercially available numerical code PISDYN was used to analyze the piston liner interface. The Finite Element (FE) models of piston and the liner were used to simulate Elasto-Hydrodynamic Lubrication (EHL) between skirt / liner and piston pin / pin hole. Friction of the numerical model was validated through a tear-down motoring of the engine. The secondary motion of the piston is studied. Understanding of how the profile and the ovality of the piston skirt affects the friction, wear and impact force at the piston liner interface is gathered. Asymmetrical skirt profile is proposed and its utility to reduce the thrust force on the liner and hence its friction and vibration of the engine is explained. The importance of piston-liner cold clearance, viscosity and liner surface roughness on skirt lubrication, friction and wear is understood. Also how piston pin offset and piston mass affects the thrust forces is seen. Based on the above understandings, conditions which would aid engine seizure and how it can be avoided are explained. Copyright © 2014 SAE International and Copyright © 2014 TSAE.
Mohite U.,Mahindra Two Wheelers Ltd. |
Bhavsar P.,Mahindra Two Wheelers Ltd.
SAE Technical Papers | Year: 2014
In this paper the approach to predict vibrations in motorcycles is presented. It can be divided mainly in two parts: prediction of engine forces using multi body dynamics (MBD) simulation and prediction of vibration response using FEA. Dynamic forces predicted at each engine mount through MBD simulation are used as input to FE analysis for vibration prediction. Single cylinder SI engine having primary balancer shaft is considered to develop this methodology. Flexibilities of important parts are considered for MBD simulation. Crankshaft ball bearing which is used in almost all two wheeler engine is modeled with 6×6 stiffness matrix. It provides coupling between radial, axial and tilting deflections of bearing and it also allows moment transfer from crankshaft to casing. This helps to predict realistic forces at each bearing and engine mounts. Distribution of primary and secondary forces at crank bearings and at different engine mounts is studied. Forces predicted from MBD simulation at each engine mounts are applied to full vehicle FE model. Forced response is predicted at each TSP and compared with test response at same point. It was found that predicted response was in well agreement with test response. Based on understanding of distribution of forces it is decided to increase mount stiffness of the support experiencing more force. This in turn helped to reduce vibration at TSP. This approach is effective to predict vibrations in early design stage to reduce development cost and time. Copyright © 2014 SAE International and Copyright © 2014 TSAE.
Jain A.,Mahindra Two Wheelers Ltd.
SAE Technical Papers | Year: 2015
Conventional motorcycle swingarm design includes steel tubing and sheet metal structures. Conventional swingarm are inherently over-designed as their design comprises of tubular structures of same cross section through the entire length of the swingarm, whereas the stress induced varies along the length (maximum near the frame pivot). An aluminum alloy swingarm design even when subjected to casting manufacturing constraints, has the potential for better material layout and weight minimization. But obtaining an ideal material layout for maximum performance can be a challenge as it requires a number of time consuming design iteration cycles. This paper aims to use concept based design methodology for design of aluminum alloy swing arm by application of topology optimization techniques to meet styling and structural targets and thus, obtain an end user product. This paper demonstrates the use of a concept based design approach in contrast to the conventional experience based approach. The concept based designing can be deemed to be more profitable and as it greatly reduces design iteration cycle time. Copyright © 2015 SAE International.